Merco 86007, Руководство по запчастям и обслуживанию

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MHC-1 Service Manual 4
TROUBLESHOOTING GUIDE
SYMPTOM POSSIBLE CAUSE EVALUATION
Holding Cabinet will
not heat Incoming Power Supply Verify power cord is secured firmly in receptacle.
Measure the incoming voltage. Check circuit
breakers. Reset if required. Call power company
if needed.
Power Switch Check continuity between switch terminals.
Replace switch as needed.
Power Board Make sure wires are connected properly including
ribbon cable. Check ground wire (green wires)
including main power cable. Make sure the unit is
grounded properly. If everything is right, replace
the control board.
Unit doesn’t reach
desired temperature Thermocouple Check for continuity in circuit.
Heat Element Compare cavity temperature with display reading.
Insert temperature probe into center of cavity.
Acceptable temperature variation is +/- 20° from
display reading.
Check for loose connection.
Check the Amp draw on each element for proper
load. Check page 2 for rating information. If the
amp draw is high or low, check the individual
elements for opens, shorts and proper resistance.
WITH POWER OFF: To check resistance of the
elements, remove all leads from the elements and
use a digital multimeter.
The element resistance should be as follows:
120V – 87 ohms
Replace heating element (shelf) as needed.
Check thermostat (common wire). Please note
that if thermostat is bad, both circuits will be bad.
Temperature is too
high Thermocouple Check for incorrectly wired thermocouple.
Thermocouple wire polarities are reversed.
Heat Element Compare cavity temperature with display reading.
Insert temperature probe into center of cavity.
Acceptable temperature variation is +/- 20° from
display reading.
Check for loose connection.
Check the Amp draw on each element for proper
load. Check page 2 for rating information. If the
amp draw is high or low, check the individual
elements for opens, shorts and proper resistance.
WITH POWER OFF: To check resistance of the
elements, remove all leads from the elements and
use a digital multimeter.
The element resistance should be as follows:
120V – 87 ohms
Replace heating element (shelf) as needed.